1. Field of the Invention
This invention relates to a grinding apparatus for an edge of a silicon wafer, etc., which are materials for a semiconductor element, and more particularly to a grinding apparatus for an edge of a silicon wafer, which carries out chamfering and polishing for the wafer edge.
2. Description of the Related Art
A silicon ingot, etc., which are materials for a semiconductor element, are sliced into wafers by a slicing machine. Because the outer peripheral of the wafer has an edge (the outer peripheral surface of the wafer is substantially perpendicular to a cutting face), clippings and cracks easily appear due to a little shock on the outer peripheral part of the wafer. That is why the wafer having been sliced by the slicing machine is chamfered before the lapping with a lapping machine. And, recently, because of the high integration of the wafer, not only the chamfering for the wafer edge but also the polishing for the chamfered wafer is performed.
Conventionally, the chamfering and the polishing are respectively carried out in different apparatuses. There is a chamfering apparatus which is modified to perform the polishing as well as the chamfering, but this apparatus uses a forming urethane, etc. instead of a grindstone. A mechano-chemical abrasive, a mixture of caustic soda (poison) and a powder silica, which are difficult to handle, instead of widely-used water soluble coolant. However, in the case when the chamfering and the polishing for the wafer are performed in different apparatuses, there is a problem in that the cost of equipment is high and a large space is required.
Moreover, the mechano-chemical abrasive is employed in the chamfering apparatus which is modified to perform the polishing. Therefore, there is a problem in that the abrasive cannot be easily handled. Further, some equipments are required for a special equipment for supplying abrasive.